This invention relates to a data transfer device system and a network system including the data transfer device system.
The technical field of this invention includes background techniques such as JP 2008-136013 A (Patent Literature 1), JP 2013-102546 A (Patent Literature 2), and JP 2013-51481 A (Patent Literature 3).
Patent Literature 1 states: As apparatuses which construct a ring network, a structure including a monitoring apparatus and other relay apparatuses is employed. The monitoring apparatus monitors only a ring status of such a ring network to which the own monitoring apparatus belongs. The monitoring apparatus periodically transmits health check frames from ring ports thereof respectively so as to monitor whether or not the transmitted health check frame has been received by the ring port located opposite thereto. Also, in a structure of a multi-ring network having a shared link, auxiliary health check frames are periodically transmitted from two sets of shared apparatuses respectively with respect to a monitoring apparatus of a shared link non-monitored ring network. The monitoring apparatus also monitors the auxiliary health check frames in combination with the health check frames in order to avoid an occurrence of a loop which bridges a plurality of ring networks.
Patent Literature 2 states: In packet relay devices which can be virtually seen as a single unit by linking the plurality of devices, the flow of communication or communication volume is automatically determined by having a link optimization adjustment or a packet analysis part and traffic flowing in a control part is controlled to compensate the band shortage by optimizing lines to be mainly driven.
Patent Literature 3 states: In a ring network including an old master node, a new master node is used as a replacement for the old master node. During replacement operation, when detecting that two ring ports of the new master node are set in link-up state, the new master node gives a transit node an instruction to forward a health check frame sent from a ring port of the old master node by a forwarding route going through the new master node. The new master node can monitor the status of the ring network by receiving the health check frame.